Canadian health officials are warning consumers to avoid romaine lettuce grown in Salinas, Calif., because of another food poisoning outbreak.

The notice comes almost exactly one year after a similar outbreak led to a blanket warning about romaine, ranging from whole heads to pre-cut salad mixes.

The Public Health Agency of Canada says one patient in Manitoba last month suffered from an illness bearing a “similar genetic fingerprint” to illnesses reported in an ongoing U.S. investigation into an outbreak of E. coli in the Golden State.

Health officials say an outbreak is not occurring in Canada, but romaine from northern California is imported north of the border this time of the year.

The agency says it is implementing “new actions” at the border to prevent the tainted lettuce from coming into Canada.

Leafy greens can become contaminated after contact with feces from infected animals via soil, water or improperly composted manure.

This is the fourth E. coli outbreak linked to romaine lettuce affecting Canadian consumers in the last two years.